The Wall Street Journaldiligently retraces Zuckerberg's Road to Advertising Damascus moment after Facebook's botched IPO—and the conversion to true mobile believers has proved fruitful. Later this month, analyst expect to announce that Facebook's 2013 revenue grew 40 percent from 2012, with $3 billion (a third of total revenue) coming from mobile advertising.

But because Zuck has pointedly said there's "no point right now in having a massive profit" from his social revolution and bragged that the ad business "factors in, like, not at all" into decisions that affect users, then (like fellow traveller David Karp), he needs a mythology makeover.

And after turning a website born in his college dorm room into a company valued at $100 billion, the young chief executive was under pressure to prove he could sell lots of ads on smartphones.

So he went for a long walk a few weeks later through the center of Facebook's corporate campus here with Andrew "Boz" Bosworth, a top engineer at Facebook and friend who once was Mr. Zuckerberg's teaching assistant at Harvard University.

"Wouldn't it be fun to build a billion-dollar business in six months?" Mr. Zuckerberg asked. He wanted Mr. Bosworth to help lead the company's shaky mobile-ad business, then bringing in almost nothing. Another part of the job: figure out all the ways Facebook could make money.

Ads didn't sound like fun to Mr. Bosworth, but his boss persisted. Soon, the engineer was filling in the blanks of a spreadsheet that grew to about 80 pages long. The entries became the manifesto of an in-house project that Mr. Zuckerberg called "Prioritization."

2. Money doesn't matter.

Trying to copy Snapchat and get smartphone users hooked on chatheads has failed, but Facebook has found indisputable success in making money off ads—and related revenue streams. Just don't say that in front the fragile CEO:

Yesterday, during a Senate commerce committee meeting about data brokers—which make $156 billion…
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Mr. Zuckerberg bristles at the view of some people close to him that he has changed as a CEO. His primary mission still is to connect the world digitally with Facebook. "It drives me crazy when people write stuff and assert that we're doing something because the goal is to make a lot of money," he says.

3. I wish I were a fry cook!

The "often-stubborn, idealistic 29-year-old" has figured out how to relate to advertising clients with all the overzealous insincerity of a glad-handing politician:

At a visit last summer to the headquarters of Facebook ad client McDonald's in Oak Brook, Ill., he learned how to cook an egg-white breakfast sandwich and asked the head of french fry taste tests why one batch he tasted looked a few shades lighter than fries served in McDonald's restaurants.

Her answer: French fries sold at McDonald's are cooked in oil that has been through multiple fry cycles. Mr. Zuckerberg said: "You have the greatest job ever." His own Facebook page has long been peppered with McDonald's and Chicken McNuggets references.

4. He learned this by watching you, users.

When young Zuckerberg retells his own advertising conversion story, he sees himself as a leader who merely follows where his users want to go:

Some of the changes at Facebook remind him of walkways at his old high school, Phillips Exeter Academy in New Hampshire. As a student, he was befuddled by a meandering path to the campus cafe. The route seemed strange, so Mr. Zuckerberg did some research.

The answer? "Instead of choosing the path up front, they kind of waited and saw where people walked and put a path where people walked," he says.

Log in to Facebook right now. Look around at the cornucopia of bountiful Sponsored ads, regular ads, Suggested Posts, and Upworthy links. When you only see one set of footsteps, that is when Zuck was carrying you.